The transmission in my 87 442 has nice firm shifts. However, it doesn't fully go into overdrive. What I mean by that is I can feel it shift through all gears but once it gets into 4th and I am crusin at highway speeds my rpm's don't drop. I'll go about 65mph and the tach will read 3k where as in the Monte Carlo I had before would read 2,500 or so. Anybody have any ideas? Thanks in advance